Electrical power producing wind turbines are a supplement to power generating stations using fossil fuels or nuclear fuel to produce electricity. The primary components of current wind turbines are blades, blade shafts, a gear train and a generator. The gear train increases the speed of rotation of the shaft to run the generator at higher speeds of rotation than the turbine blades are rotating. The gear train and the generator combine to weigh more than twenty tons in many modern wind turbine implementations. A sample gear train is shown at 60 in FIG. 1, with the blade shaft 61 being coupled with a larger gear 62, which can then interact with appropriately sized intermediate gears 63 and a generator shaft gear 64 to drive the generator shaft 65.
Current wind turbines locate the primary system components at the upper end of the support structure, sometimes exceeding 300 feet in the air. Putting all of the mechanical equipment at great height creates installation and maintenance problems, especially in inclement weather. In many areas, cranes cannot service the wind turbine during the winter months. Additionally, wind turbine support systems must be designed to handle the extreme weight at such high altitudes.
A nacelle is normally provided to house the gear train and generator at blade shaft level, adding to the wind resistance at the top of the structure and as an attraction for lightning since it is solidly grounded to the supporting tower. Having the generator at height subjects it to lightning strikes that can severely damage the generator and the electrical connections to ground level. Both the tower and the generator electrical conductors act as a direct high conductance path for lightning to ground potential.
The wind turbine blades, being at an elevated height in relationship to surrounding structures, become much like a lightning rod and attract any potential lightning strikes in the area. Lightning damage to the wind turbine blades are expensive to repair and in many instances can cause damage to the supporting tower due to the imbalance caused by the damaged blade as it rotates. Cost of the blades is magnified by the insertion of electrically conductive cables and/or metal screening in an attempt to direct the lightning current directly to the support tower without the current traveling over or through the blade external material.